Magnetic and Mössbauer Spectral Study of Mixed Valent La₀.₂Sr₀.₈Cu₀.₂Fe₀.₈O_2.68 and Related Perovskites

Author

Gary J. Long, Missouri University of Science and TechnologyFollow
Dimitri Hautot
Amitabh Mohan
Ingeborg Kaus
Harlan U. Anderson, Missouri University of Science and TechnologyFollow
Fernande Grandjean, Missouri University of Science and TechnologyFollow

Abstract

The La_0.2Sr_0.8Cu_1-xFe_xO _3-δ perovskites are important because they are mixed electron and oxygen anion conductors and thus are able to serve as dense oxygen separation membranes. In order to better understand the mechanism for this separation a Mössbauer spectral study has been carried out to determine the ratio of iron(III) to iron(IV) in these mixed valent compounds. The Mössbauer spectra of La_0.2Sr_0.8Cu_0.2Fe_0.8O _3-δ obtained between 4.2 and 78 K reveal that its Néel temperature is ~75 K and the two well-resolved magnetic sextets observed between 4.2 and 45 K indicate the presence of trapped valence iron(III) and iron(IV). At 4.2 K the respective hyperfine fields are 454 and 299 kOe and the isomer shifts are 0.388 and 0.057 mm/s. The iron(III) to iron(IV) ratio is 1.20, a ratio which yields a δ value of 0.32 and, if one assumes the presence of only copper(II), a corresponding stoichiometry of La_0.2Sr_0.8Cu_0.2Fe_0.8O _2.68.

Recommended Citation

G. J. Long et al., "Magnetic and Mössbauer Spectral Study of Mixed Valent La₀.₂Sr₀.₈Cu₀.₂Fe₀.₈O_2.68 and Related Perovskites," Journal of Applied Physics, vol. 85, no. 8 II B, pp. 5341 - 5343, American Institute of Physics (AIP), Apr 1999.

The definitive version is available at https://doi.org/10.1063/1.370246

Department(s)

Chemistry

Second Department

Materials Science and Engineering

International Standard Serial Number (ISSN)

0021-8979

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 1999 American Institute of Physics (AIP), All rights reserved.

Publication Date

01 Apr 1999